/Engine/Source/Editor/UnrealEd/Public/FbxImporter.h
Check if two faces belongs to same smoothing group
bool true if two faces belongs to same group
bool FacesAreSmoothlyConnected ( [FSkeletalMeshImportData](API\Runtime\Engine\Rendering\FSkeletalMeshImportData) & ImportData, int32 Face1, int32 Face2 )